Wire bonders are generally used to connect wires between a semiconductor chip and a substrate. In particular, wedge wire bonders are used to bond heavy wires such as aluminum wire, especially on high power electronic packages. The wedge wire bonder has a bond head that is able to position itself relative to the electronic packages in the X, Y, Z and theta axes for wedge bonding. Having a theta axis is necessary in wedge bonging for aligning the bond head orientation with the wire being fed between a first bond and a second bond.
The bond head further comprises a vibration-generating transducer, such as an ultrasonic transducer, an amplifying horn, and a bonding tool in the form of a wedge attached at one end of the amplifying horn for conducting bonding. Due to the various movement axes of the bond head, the bonding tool needs to be adjusted and aligned along the corresponding axes so as to perform wire bonding operations accurately.
Adjustment of the bonding tool is generally performed manually prior to commencing wire bonding operations. For this purpose, the wire bonding machine usually provides a feature to aid the operator to set up the bonding tool and to fix its position correctly, since the size of the bonding tool is small. A camera may be used to capture an image of the bonding tool and to display it on a monitor. Marking lines representing limits of a tolerance range is overlaid onto the display to facilitate positioning of the bonding tool.
U.S. Pat. No. 7,591,408 entitled “Camera-assisted adjustment of bonding head elements” discloses a method for adjusting a bond head element in relation to an ultrasonic tool. The tip of the ultrasonic tool is optically detected by means of a camera and is displayed in an image on a display device. Markings comprising lines illustrating a tolerance range is superimposed in the display in real time as a positioning aid in order to facilitate adjustment of the ultrasonic tool.
A shortcoming of the approach disclosed in the aforesaid patent is that it requires an additional and relatively complicated set-up procedure to generate and draw the marking lines defining the tolerance field. Further, the marking lines only guide the edge position of the bonding tool, such that it does not assist in adjustment of the bond tool orientation where the bonding tool orientation is incorrect.